Cook the potatoes and white part of green onions in boiling salted water in their skins for 35-40 min. Drain, douse the potatoes with cold water and peel. Mash the potatoes with the help of the pusher in the puree. Mix with 4 cups of flour, dried rosemary and 1 tsp of salt so that the mixture resembled crumbs.
Mix the yeast with 1 Cup warm water, leave until the mixture starts to foam, 5-10 minutes. Gradually add the water with yeast into the potato-flour paste, add 2 tbsp oil, knead until smooth. Perello-keep the dough on a floured surface and knead by hand 8-10 minutes, until elastic. Pour more flour in small portions, as needed.
Grease large bowl, roll the dough into a ball, place in a bowl and turn the ball a few times, so it was completely coated with a film of oil. Cover with a towel and leave in a warm place for 1.5–2 hours
Put the dough on a baking sheet and shape by hand from a rectangle of about 30 x 40 cm Cover with a towel and let rise again in warm place 35-45 minutes. Crush the peeled cloves of garlic with the flat side of a knife, mince the leaves of fresh rosemary, cover the garlic with rosemary oil, set aside for at least 30 min.
Potatoes wash brush and cut into very thin circles. Exactly put slices of potatoes on the dough in rows, overlapping. Remove the garlic from the oil, pour the oil with the rosemary potatoes. Season with salt and pepper.
Put the pan with Focaccia in the lower third of the oven, preheated to 200 °C. Bake until Golden brown, 45-50 minutes. Serve Focaccia bread, cut in triangles or strips, warm or cold.